Optimizing SQL Insert Performance - GSE Belux
Optimizing SQL Insert Performance - GSE Belux
Optimizing SQL Insert Performance - GSE Belux
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Segmented Tablespace …<br />
• SEGSIZE<br />
– General recommendation is to use large SEGSIZE value consistent t with size of pageset<br />
• Typical SEGSIZE value 32 or 64<br />
– Large SEGSIZE<br />
• Provides better opportunity to find space in page near by to candidate page and<br />
therefore maintain clustering<br />
• Better chance to avoid exhaustive space search<br />
– Small SEGSIZE<br />
• Can reduce spacemap p page contention<br />
• But less chance of hitting ‘False Lead Threshold’ and looking for space at the end of<br />
pageset/partition<br />
‘False Lead’ is when spacemap page indicates there is a data page with room for the row,<br />
but on visit to the respective data page this is not the case<br />
• Also applies to Universal Table Space (DB2 9)<br />
12<br />
© 2010 IBM Corporation
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